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The History of Astronomy at RPI

The Proudfit Observatory

The history of astronomy at RPI actually dates back several decades
before the formation of RAS in 1938. Astronomy had been taught as a core
discipline since the formation of the school in 1824, but there is very
little in the historical record about what activities took place.
Astronomy began in earnest at RPI in 1875 when Mr. and Mrs. Ebenezer
Proudfit of Troy donated $15,000 to build an impressive observatory
named the William Proudfit Observatory.[2] The history of
this observatory is an interesting study in failed initiative. The
observatory was named in honor of the Proudfit’s son, an RPI student in
the class of 1877 who died in a tragic stagecoach accident at the age of
19. On November 10, 1875, the trustees accepted a proposal by the Proudfits
to build an observatory in his honor, noting that the gift was not only
a valuable contribution to science and learning, but also an
appropriate memorial to their lamented son”.[1] The
building was constructed on the precipice of the hill near where Walker
Lab now stands. Some of the foundations of the building may still be
intact, lying beneath what is now a small garden. The central part of
this building was two stories high, and was topped with an impressive
dome measuring 29 feet in diameter. The original design intended the
eastern wing to be used for “meridian instruments” while the western
wing would be used for “computation and a library”. The dome was by far
the most interesting feature of this building and was innovative in
being one of the first paper domes constructed. The Hall process had not
been invented, so aluminum was still more expensive than gold, and paper
was a practical material. The design and construction was overseen by
Prof. Dascom Greene, a professor of mathematics and astronomy, who may
be considered the inventor of the paper design. Prof. Greene provided
the following rationale for paper construction:

“I ascertained that a dome of the dimensions required, constructed in
any of the methods in common use, would weigh five to ten tons, and
require the aid of cumbersome machinery to move it. It therefore
occurred to me to obviate this objection by making the frame-work of
wood, of the greatest lightness consistent with the requisite
strength, and covering it with paper of a quality similar to that used
in the manufacture of paper boats; the principal advantages in the use
of these materials being that they admit of great perfection of form
and finish, and give extreme lightness, strength, and stiffness in the
structure…”

Prof. Greene contracted E. Waters & Sons, a firm in Troy known for boat
manufacture, to work on the project. In 1878 they finished the paper
observatory dome for the newly erected building. The construction method
was almost identical to that used for paper boats: thick linen paper was
formed over a mold with a wooden framework, which was removed from the
mold along with the paper. Finished sections were bolted together and
the joints were weatherproofed with cotton cloth saturated with white
lead. The RPI dome was 29 feet in diameter and consisted of 16 sections
plus a 4-foot wide shuttered opening for the telescope. The paper
material was 1/6 of an inch thick and was described as “hard as
wood”.[4] It weighed 4000 pounds, of which paper probably
accounted for 1000 pounds. The dome was supported by six eight-inch
cannon balls, which moved between grooved iron tracks, allowing the dome
to “be easily revolved by a moderate pressure applied directly without
the aid of machinery.”[3] The method of paper dome
construction was utilized in several other observatories in the
Northeast, including one at West Point.[5] A patent was
issued to E. Waters & Sons in 1881.

Sadly, a large telescope was never housed in the observatory due to lack
of funding. However, the 1879 Record of Science and Industry lists the
Proudfit as an active observatory, with Prof. Dascom Greene as director.
They note that it did not yet contain a large instrument on the main
pier, but did have the following instruments:

Transit Instrument. by Kubel, of Washington, of 2 inches aperture
and 31 inches focal length. It is so made as to admit of ready
reversal, and is provided with delicate Level and Micrometer, to adapt
it for use as a zenith telescope.Another Transit. of 2 inches aperture and 30 inches focal length, is
mounted in the prime vertical.Telescope, by Fitz, of 3 inches aperture, mounted on an equatorial
stand.
For furnishing the time, there are two mean Solar Clocks and a
Sidereal Chronometer.[6]

The present status of these instruments in unknown, but they may have
been donated to the Smithsonian or another museum, as has occurred with
several other relics at RPI.

Because a large telescope was never placed in the dome, it was never
much use to the university. In 1900 the dome was replaced by a roof and
a second story was added to the three wings. As is a common occurrence
throughout Troy and RPI history, the building was partially destroyed by
fire in 1902. As part of the renovation in 1903, a third story was added
and the basement deepened. The building became a laboratory for
mechanical and electrical engineering. The building went through several
renovations and other uses and was eventually razed in 1959. The only
physical reminder of this structure is the archway keystone which is
memorialized on the southern entrance of the Science Center in
1961.[2]

Formation of the Rensselaer Astrophysical Society

The Rensselaer Astrophysical Society was founded by students in 1938. In
1940 the Board of Trustees approved the Society’s proposal to erect an
observatory on the campus, which became known as “Rensselaer
Observatory”. The observatory was designed by Dr. Ralph Winslow, head of
the school of architecture, and construction was supervised by
Physics Professor G. Howard Carragan. It was
built on a small ridge just south of Russell Sage Dining Hall, where the
Low Center now stands. The observatory was dedicated
in September 1942 in an address by Professor Bart J. Bok, then a member
of Harvard College Observatory. The 12” reflector was built on
campus was sheltered under a 16’ dome. The observatory was featured in
the October of 1942 issue of Sky and Telescope Magazine. (see scans
above)

The 12” equatorial reflector is shown in use prior to the observatory
(left) as well at the 1942 dedication. Today, the instrument sits on
display in the lobby of the observatory as a testament to the fine
craftsmanship of Otto Rasmussen, the department’s instrument maker, who
oversaw the construction effort, as well as the RAS members who
assisted. Mr. and Mrs. Rasmussen also donated an astronomical clock,
the present whereabouts of which is unknown.

The Observatory, circa 1942.

The Original Observatory Layout

During that time, a special radio frequency clock was used, which
received time signals from Washington. The Rensselaer Observatory also
had a variety of smaller instruments. In 1946, two refracting telescopes
were donated to the observatory. The first was a 6” refractor, given by
Mr. Roland B. Bourne (‘20), which was mounted on a B-29 gun turret. The
second was a 5 1/4” refractor given by Mr. Gabriel R. Solomon
‘02.[1][2] It is believed that this telescope is the 1883
John Byrne refractor which still remains at the observatory. Mr. Solomon
was a distinguished graduate, a professional engineer and businessman
who traveled the world and became rich working as a civil, mechanical
and electrical engineer.[3] We also know that the
observatory had a 3 1/2” refractor, and a 3” Ross photographic telescope
with a Ross-Fecker camera. There was also a small solar observatory and
heliostat outside, which tracked the sun and reflected a beam of
sunlight into the building. Additionally, when Mr. Rasmussen retired in
1952, his 6” reflector was purchased by the physics
department.[2] The observatory continued to be a popular
local attraction. In 1954, 900 visitors were reported to have visited
the observatory, [2] and in 1957 there were 2400 visitors.

Radio Astronomy and the Sampson Station

Today not many people realize that RPI was once a hotbed for radio
astronomy. The campaign to bring radio astronomy to RPI was led by Dr.
Robert Fleischer. Dr. Fleischer was very dedicated to expanding
astrophysical research at RPI and also dedicated numerous hours sharing
science with the public at the Rensselaer Observatory. He was went to
school at Harvard, receiving his BS in 1940, MA in 1947, and PhD in
1949, with research interests in geophysics and solar-terrestrial
relations. Fleischer joined the faculty at RPI, advancing to Full
Professor in 1958. His obituary states “It is a testament to his
character that without his enormous energy, organizational, and
fundraising abilities, the radio telescope project languished after he
left.”[1] Dr. Fleischer had big dreams for astronomy at
RPI, a few of which came to fruition, while others are now left for
future generations to fulfill.

In January 1956, Dr. Fleischer wrote a lengthily proposal arguing that
the venerable Dudley Observatory should merge with RPI and construct a
new observatory at a site in Grafton Lakes State Park. This new
observatory would house the Dudley’s precious 13” 1860 refractor and 12”
1893 Pruyn Equatorial Telescope as well as an extensive library of rare
books. Furthermore, a new radio telescope would be constructed at the
site, the plans for which had apparently had already been discussed.
Ultimately, the merger did not happen, but Dudley, along with Union
College, teamed with RPI to help build and operate a radio observatory
on an 820 acre tract of land in Grafton Lakes State Park. The site was
chosen because of its relative isolation from electrical lines and other
sources of radio noise. The station was named “Sampson Station” in honor
of Dr. John A Sampson, who bequeathed the property to
RPI.[2] A dedication ceremony was held on June 30, 1957 in
conjunction with the opening of the International Geophysical
Year.[2] The observatory complex was powered by a generator
until a 1-mile underground electric line was completed later in 1957. A
$50,000 grant was received from the Research Corporation as well as
$30,000 in annual funding from the NSF. Additionally, the trustees of
the Dudley provided funding, as part of the joint venture. Research
staff included Dr. Alan S. Meltzer, Dr Pearl R. Lichtenstein, along with
research associates Mr. Robert L Watters and Dr. Kenneth Mortenson.

Picture taken by Dan Elton in 2009

I found a map of the observing site and decided to go to Grafton to look
for any remains of the radio telescope. The picture above is a
trailer I found after walking about 2 miles down a trail at the end of
Shaver road at Grafton Lakes State park. A gate and sign announced that
I was entering private property of RPI. It said No Trespassing, however,
the same trail is on the Grafton map, so it appears to be part of the
park now. I found the remains of the trailer at what I believe is a
location marked on the map as “summer buildings”. Two buildings where
shown on the map in fairly close proximity, but I only found one. It was
nearly destroyed, as you can see. One reason this may have been part of
the observatory is that I found an electrical conduit coming out of the
ground, so it appears a buried electrical line came to the trailer at
one time. I also found a field which may have been part of the
observatory. Large pieces of corrugated metal were strewn in various
places. A large part of the RPI property and trails was left
unexplored.

A fair amount of research was performed on auroral noise and solar radio
noise at Sampson Station. An abstract from 1961 discusses a
517-megacycle swept lobe interferometer with spacing of 200 feet between
elements. Dr. Fleischer outlined plans to build mobile radio telescopes
in buses with the seats removed. These telescopes could be constructed
and then moved into position as desired. They could be rearranged to
make a larger or smaller baseline depending on the sensitivity and
resolution required. It is not known whether this project was
completed. It is sad that after Dr. Fleischer left to work at the NSF
in 1962, work at the radio observatory quickly subsided.

However, we do know that someone at RPI named J. Spalding had ambitious
plans of his own.. He had ordered quotes for a 24” and 16” f/4
reflectors from Boiler and Chivens in 1963, and had drawn up detailed
blueprints and plans for what he described as a “optical-radio
observatory”, which included a “high power laser”. The purpose of this
laser is not elucidated, but it was of such size that the plans
specified a special room for the power supply. (Its likely the laser was
for an early type of adaptive optics system, i.e. monitoring atmospheric
turbulence, or some kind of interferometer, however that would require
two telescopes, and there is only one in the plans). The plans say that
it would be located at the “Crawford road site”. (there is a Crawford
Road in Schenectady, NY). Evidently, none of these plans ever came to
fruition.

It is not clear exactly how and when radio astronomy died at RPI, but by
the 1970s the Sampson station was abandoned.

The Hirsch Observatory

In 1980 the General Electric company donated the Boller and Chivens 16”
Cassegrain telescope currently in use. The age of the telescope is not
known exactly, but it was probably built in the mid 60s. The use of this
telescope by GE prior to 1980 is also unknown, but it is the personal
guess of the author that it may have been used for tracking high
altitude aircraft. The extra-long focal length and high magnification
would make it ideal for such purposes.

The observatory was expanded and re-dedicated to celebrate the event. A
second dome was built to house the new telescope, since it was felt that
the process of replacing the original telescope with the new one would
cost more than simply building a new dome.

The observatory immediately became known as the “Dolly Parton
Observatory” for rather obvious reasons. As a matter of fact, as a
prank, a group of students painted the tops of both domes red, added red
plastic buckets to the structure, and then covered the entire thing with
a “brassiere” made out of bed sheets.[1]

Between 1983 and 1984 the observatory was moved (reduced in size) to the
roof of the Science Center to make room for the Low Center for
Industrial Innovation. The observatory was renamed the Hirsch
Observatory, in honor of Hope and David Hirsch, Class of 1965 and
Rensselaer Trustee, who donated money for the renovation. The telescope
was mounted on top one of the concrete piers running through the
building to provide a stable mount. Between 1980 and 1995 the
observatory was used for photographic imaging but was not open to the
public regularly. RPI student Nicole Zellner is responsible for starting
the present-day public observing program in 1996. She graduated from RPI
with a PhD in Multidisciplinary Science in 2001 and went on to become a
professor of astrophysics and planetary science at Albion College.

In 2006 there was a $70,000 refurbishment, in which the control system and
electronics were re-vamped and the telescope optics collimated. Dr.
Peter Mack from Astronomical Consultants and Equipment (ACE) was
contracted for the refurbishment. (Mack can be seen with RAS president
Anthony Milano in the picture above.) The dome and telescope were
automated with the same type of control systems found in all the world’s
major research observatories. The institute considered replacing the
telescope with a new one, but decided not to, since the current scope is
very robust and is much heavier and stable than many newer scopes.

Today the Hirsch Observatory is used by members of the Astrophysical
Society as well as students in their laboratory exercises. The RAS and
members of the Physics Department offer frequent public viewing
sessions
at the observatory every Saturday evening 8-10pm from February to
mid-November. The observatory averages around 800-900 visitors per year,
and with increased publicity and outreach, this number is expected to
rise.

Long time volunteer Johnathan Cassidy has logged countless hours at the observatory educating young people about astronomy and inspiring them to pursue careers in science. He is pictured here in a picture from circa 2006-2008 and has remained active at the observatory through 2019.

Notes on the 1883 John Byrne Refractor

(written by Dan Elton in 2009)

This telescope is a historic brass refractor bearing the signature of telescope maker John Byrne - 1883. According to some records found at the library and online, the RAS had several telescopes donated in the 1940s.( see “Reports of Observations”, Astronomical Journal, 1954) One was a 5 1/4” refractor given by Mr. Gabriel R. Solomon ‘02 around 1942. It is believed that this is the Byrne refractor we have today. Mr. Solomon was a distinguished graduate, a professional engineer and businessman. As far as John Byrne himself, he started as an apprentice of telescope maker Henry Fitz in 1847 and worked with him until Fitz’s death in 1863. He then began making Byrne signed telescopes. Earlier telescopes were f 15, and the later models were an innovation in being f9 to f10.5. A 5 inch Byrne similar to this one was used by the well know astronomer Edward Barnard to discover several comets. Also, George Hale’s second telescope was a 4” Byrne refractor. Hale went on to found the Yerkes, Mount Wilson, and Palomar observatories. This instrument is currently in a state of disrepair. It is missing its original pier mount and some elements of the focuser. It is hoped that is can be restored into working order. (here is a brief bio on Byrne)

Pictures from 2008-2009 (taken by Michael Cantore):

Archives - Mirror Overhaul Project

(Completed Summer 1998)
(This was from the old RAS website and written by Jeffrey LaCombe)

As with any viewing instrument, the quality of the image is determined
by the quality of the optics. In the summer of 1998 the RAS took the
primary mirror on the 16” Cassegranian telescope in for servicing. This
is how we did it.

Disassembly

The process of overhauling the primary mirror on the Hirsch
Observatory’s 16” Classical Cassegranian telescope began with a thorough
inspection of the telescope construction. It was first determined that
the focusing drawtube needed to be removed, to allow inspection of the
back side of the primary mirror cell. Additionally, the counter-weights
and the cone were also to be removed to allow access to the bolts which
attach the primary mirror cell to the Optical Tube Assembly (OTA).
Additionally, any parts of the guide scopes or support equipment and
wires were removed or restrained so as to allow easier working
conditions. From here, it was anticipated that the mirror and the cell
would probably weigh quite a bit, and that it would be necessary to
exercise caution when detaching these from the
OTA.

The mirror was removed with the assistance of a temporary wooden
structure constructed of 2x3 studs. The weight of the mirror and cell is
probably in the 75lb range, and hence can be difficult to maneuver once
the attachment bolts are removed. Two people at the minimum are
necessary to lift the mirror into its final position, with additional
people helping lift and inserting or removing the attachment bolts that
join the cell assembly to the OTA.

When disassembled, there are many parts to keep track of. Here we see
the various major components that were detached during the procedure
(left). Starting at the upper left and moving clockwise, we have the
primary mirror, the mirror retaining ring, the light baffle, assorted
counter-weights, the mirror cell, the focuser drawtube, and the cone.

A degree of confusion was encountered when trying to detach the mirror
backing plate from the mirror.

This is accomplished first by removing the retaining ring from the front
via the socket cap screws. However, at this point, it is likely that the
backing is still firmly attached to the mirror. The backing is removed by
loosening the four set screws that extend into the backing plate from the rear
(along the edges of the center tube) and cause friction pads located in the tube
to expand their diameter and thereby allow adjustment (left-right etc.) of
the primer mirror. Once these set screws are loosened, the backing plate
should detach from the mirror.

Mirror Alignment and Collimation

By the time of its completion, the mechanical aspects of the project
would prove to be the easier part. The best resource that could be found
on the subject was the book “Star Testing Astronomical Telescopes” by
Harold Richard Suiter (available at
Orion).
Unfortunately however, this resource, as well as most other mentions
found online and elsewhere, only discussed adjustment of the secondary
mirror in Schmidt-Cassegranians. For the case where primary mirror
adjustment is necessary, they say something to the effect that we need
to send it to the factory for adjustment. Since we clearly can’t do
this, difficulties were in store for us!

The procedure followed was basically a best-guess adaptation of the
Newtonian optics collimation method. The details won’t be discussed
here. Instead, only the important tips will be mentioned. The first step
was to achieve the objective (described in the text) of centering the
image of the primary in the secondary mirror, as viewed from the
eyepiece (a Cheshire eyepiece was helpful). This was done by moving and
tilting the primary using the set screws that extend along the center
tube (N/E/S/W) and four set screws that were at first concealed by cover
screws with flathead screwdriver slots in them. Remove these to get
access to the set screws that control the primary mirror tilt.

At this point, the quality of the image was moderate. Further adjustment
was made via the secondary mirror, which has quite a few little screws
to confuse matters. Some of these are actually lock-down screws, so once
you figure out which to turn, the iterative process can proceed. The
schematics of the secondary apparatus are available (either in the
physics department or in the observatory) and were useful when
determining the function of each screw.

Jeffery LaCombe, RAS Member involved in the mirror overhaul project,
wrote, “At the conclusion of the rather difficult collimation process,
it is my opinion that the image quality should be considerably better.
However, it seemed that no amount of further adjustments would improve
the image. It seems that there is a degree of astigmatism, that I can’t
work out of the system. I feel that the resolving capability should be
better than it is (an 8” Celestron SCT does quite a bit better on bright
objects like Jupiter and Saturn). I can’t say if the resolution was ever
was better in its past, but it should be in an instrument of this
purported caliber. With this observation aside, it is the general
consensus of the physics department users as well as the RAS club
members that the telescope now exhibits considerably higher brightness,
and at least as much resolving capability as it did prior to the
overhaul project.”

Polar Alignment

The telescope (in general) had not been tracking all that well. Of even
greater importance, the setting circles did not operate properly. It was
suspected that these problems were likely due to inadequate polar
alignment of the equatorial mount. This was fixed by using the
star-drift method to move the mount into better alignment. Subsequent
testing has shown that the setting circles are now exceptionally useful,
and the tracking has improved to the point where any difficulties are
now attributed to the motor drive, which appears to be in need of some
work.

Resolving Ability

The September 1998 issue of Sky and Telescope magazine lists double
stars in Cepheus that can be used to test the resolving ability of a
telescope.

Pos. Angle denotes orientation of fainter star wrt brighter star
measured CCW from north. East is at 90 and west is at 270, as would
typically be seen in a telescope (i.e. east and west are swapped).

Resolution Tests

Some of the above double stars were observed to determine the resolving
limit and to get an idea of the general quality of the Campus’s
observing conditions. The sky conditions on this evening (10/19/98) were
clear (at the time of these observations) with an extremely light
haze.

Star

Resolved?

Separation

Observing Note

ε Lyr

YES?

Double-Double. Main telescope could barely split them if it did at all. Brass Refractor split one definitively, but had trouble with other (but I think it did it).

ξ Cep

YES

7.9” Mag 6.4

Pretty Easy to Split. No problems with magnitudes either.

Σ2836

YES

12” Mag 10.4

The dimmer mag 10.4 was the faintest checked here. It was not visible in the Brass Refractor.

β Cep

YES

13”

Also an easy split.

Σ2798

YES

6.4” Mag 9.9

Both the main telescope and the Brass Refractor split this double.

Σ2844

YES

11.8” Mag 10.0

Both telescopes split this pair. 10.0 was dimmest seen in Brass Refractor

Σ2843 A-B

NO

1.5” Mag 7.7

Main telescope could not split. Brass refractor may have just been able to split it?

Σ2845

NO

2.0” Mag 8.2

Main telescope could not split. I don’t think Brass Refractor did either.